Satellite image mosaic of the Terra Nova Bay area (Victoria Land, Antarctica)

This work has been carried out as part of "Programma Nazionale di Ricerche in Antartide" and was supported financially be ENEA through a joint reasearch-program on Antarctic Earth Science with the University of Siena (Italy). The geopmorphological and glaciological research, of which this work forms a part, is coordinated by Prof. Giuseppe Grombelli.

Pollen profile and age determination for sediment core M72/5_619-1 (22-GC3)

Sediments from the Black Sea, a region historically dominated by forests and steppe landscapes, are a valuable source of detailed information on the changes in regional terrestrial and aquatic environments at decadal to millennial scales. Here we present multi-proxy environmental records (pollen, dinoflagellate cysts, Ca, Ti and oxygen isotope data) from the uppermost 305 cm of the core 22-GC3 (42°13.53' N, 36°29.55' E) collected from a water depth of 838 m in the southern part of the Black Sea in 2007. The records span the last ~ 18 kyr (all ages are given in cal kyr BP). The pollen data reveal the dominance of the Artemisia-steppe in the region, suggesting rather dry/cold environments ~ 18-14.5 kyr BP. Warming/humidity increase during melt-water pulses (~ 16.1-14.5 kyr BP), indicated by d18O records from the 22-GC3 core sediment and from the Sofular Cave stalagmite, is expressed in more negative d13C values from the Sofular Cave, usually interpreted as the spreading of C3 plants. The records representing the interstadial complex (~ 14.5-12.9 kyr BP) show an increase in temperature and moisture, indicated by forest development, increased primary productivity and reduced surface run-off, whereas the switch from primary terrigenous to primary authigenic Ca origin occurs ~ 500 yr later. The Younger Dryas cooling is clearly demonstrated by more negative d13C values from the Sofular Cave and a reduction of pines. The early Holocene (11.7-8.5 kyr BP) interval reveals relatively dry conditions compared to the mostly moist and warm middle Holocene (8.5-5 kyr BP), which is characterized by the establishment of the species-rich warm mixed and temperate deciduous forests in the low elevation belt, temperate deciduous beech-hornbeam forests in the middle and cool conifer forest in upper mountain belt. The border between the early and middle Holocene in the vegetation records coincides with the opening of the Mediterranean corridor at ~ 8.3 kyr BP, as indicated by a marked change in the dinocyst assemblages and in the sediment lithology. Changes in the pollen assemblages indicate a reduction in forest cover after ~ 5 kyr BP, which was likely caused by increased anthropogenic pressure on the regional vegetation.

(Table 1) Radiocarbon ages of samples taken from five sites in north-eastern European Russia

Aim: Concepts about patterns and rates of post-glacial tree population migration are changing as a result of the increasing amount of palaeobotanical information being provided by macroscopic plant remains. Here we combine macrofossil, pollen and stomata records from five sites in north-eastern European Russia and summarize the results for the late-glacial-early Holocene transition. The late-glacial-early Holocene transition encompasses the first indications of trees (tree-type Betula, Picea abies, Abies sibirica and Larix sibirica) and subsequent forest development. Considerable time-lags between the first macrobotanical and/or stomata finds of spruce (Picea abies) and the establishment of a closed forest are reconsidered. Location: Pechora basin, north-eastern European Russia. Methods: We used plant macrofossil, stomata, pollen and radiocarbon analyses to reconstruct late-glacial and early Holocene tree establishment and forest development. The data were derived from lake sediment and peat archives. Results: Palaeobotanical data reveal an early Holocene presence (11,500-10,000 cal. yr bp) of arboreal taxa at all five sites. One site presently located in the northernmost taiga zone, shows the presence of spruce and reproducing tree birch during the late-glacial. Given the current view of post-glacial population dynamics and migration rates, it seems likely that the source area of these early tree populations in north-eastern European Russia was not located in southern Europe but that these populations had local origins. Results thus support the emerging view that the first post-glacial population expansions in non-glaciated regions at high latitudes do not reflect migration from the south but were a result of an increase in the size and density of small persisting outlying tree populations. Main conclusions: Results suggest that the area east of the margin of the Scandinavian ice sheet to the Ural Mountains had isolated patches of trees during the late-glacial and early Holocene and that these small populations acted as initial nuclei for population expansion and forest development in the early Holocene.